Epidemiology of inflammatory bowel diseases in the state of Rio Grande do Sul, Brazil

Abstract

Background: This is the first study on the epidemiology of inflammatory bowel diseases (IBDs) in Rio Grande do Sul (RS), the southernmost state of Brazil with the country's fifth largest population. Crohn's disease (CD) and ulcerative colitis (UC) are collectively termed IBDs. They have high incidence and prevalence rates in high-income countries, although in recent years there has been a change in the classic geographical distribution of IBDs, with growing rates in traditionally low-incidence regions.

Aim: To estimate the incidence and prevalence of IBDs in the RS state, Brazil, between 2014 and 2019.

Methods: This is a cross-sectional descriptive observational study. Patients with IBD who had initiated treatment and met the inclusion criteria of the RS state free drug distribution program were included. Data were obtained from registration or renewal records of the RS state specialty pharmacy. The male, female, and total populations were estimated according to mid-year data from the Brazilian Institute of Geography and Statistics, which served as a reference for calculating the incidence and prevalence rates of IBDs during the study period. Results were described using mean, standard deviation, and range.

Results: We included 1082 patients with IBD, of whom 57.5% were female and 42.5% were male. Patients with CD accounted for 72.45% of the sample, and those with UC accounted for 27.54%. IBD prevalence during the study period was 9.51 per 100000 population, of which 6.89 corresponded to people with CD and 2.62, to people with UC. Incidence rates per 100000 population/year were 2.54 in 2014, 2.61 in 2015, 1.91 in 2016, 0.80 in 2017, 0.83 in 2018, and 0.96 in 2019. The mean IBD incidence rate per 100000 population was 1.61, of which 1.17 corresponded to CD and 0.44, to UC. The mean age was 41 years, and patients were mostly aged 30-40 years. Prevalence by region was higher in the state capital metropolitan area: 12.69 per 100000 population.

Conclusion: Our results demonstrated an IBD prevalence of 9.51% and incidence of 1.61 per 100000 population. The patients were predominantly female, and CD was more prevalent than UC.

Keywords: Crohn’s disease; Epidemiology; Incidence; Inflammatory bowel diseases; Prevalence; Ulcerative colitis.

Figure 1

Age distribution and incidence rates of patients with inflammatory bowel diseases. A: Age distribution of patients with inflammatory bowel diseases (IBD) (n = 1082), state of Rio Grande do Sul, Brazil, 2014-2019; B: Age distribution of patients with Crohn’s disease (n = 784) and ulcerative colitis (n = 298), state of Rio Grande do Sul, Brazil, 2014-2019; C: Annual IBD incidence rates, new cases per 100000 population/year in the state of Rio Grande do Sul (Brazil), 2014-2019; D: Annual IBD incidence rates by age group, new cases per 100000 population/year in the state of Rio Grande do Sul (Brazil), 2014-2019.